US20210317818A1 - System and method for improved extreme load control for wind turbine rotor blades - Google Patents

System and method for improved extreme load control for wind turbine rotor blades Download PDF

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Publication number
US20210317818A1
US20210317818A1 US16/844,575 US202016844575A US2021317818A1 US 20210317818 A1 US20210317818 A1 US 20210317818A1 US 202016844575 A US202016844575 A US 202016844575A US 2021317818 A1 US2021317818 A1 US 2021317818A1
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Prior art keywords
bending moment
rotor
blade
calculating
rotor blade
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English (en)
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Francesco Perrone
Leonardo Cesar Kammer
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General Electric Renovables Espana SL
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General Electric Renovables Espana SL
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Priority to US16/844,575 priority Critical patent/US20210317818A1/en
Assigned to GENERAL ELECTRIC RENOVABLES ESPANA S.L. reassignment GENERAL ELECTRIC RENOVABLES ESPANA S.L. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: PERRONE, FRANCESCO, KAMMER, LEONARDO CESAR
Priority to EP21165673.1A priority patent/EP3892851A1/en
Priority to CN202110385951.5A priority patent/CN113530757A/zh
Publication of US20210317818A1 publication Critical patent/US20210317818A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/022—Adjusting aerodynamic properties of the blades
    • F03D7/0224—Adjusting blade pitch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/022—Adjusting aerodynamic properties of the blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/04—Automatic control; Regulation
    • F03D7/042—Automatic control; Regulation by means of an electrical or electronic controller
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/028—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power
    • F03D7/0288—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power in relation to clearance between the blade and the tower, i.e. preventing tower strike
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/04—Automatic control; Regulation
    • F03D7/042—Automatic control; Regulation by means of an electrical or electronic controller
    • F03D7/043—Automatic control; Regulation by means of an electrical or electronic controller characterised by the type of control logic
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0016—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings of aircraft wings or blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/70—Adjusting of angle of incidence or attack of rotating blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/322—Control parameters, e.g. input parameters the detection or prediction of a wind gust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/331—Mechanical loads
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/332—Maximum loads or fatigue criteria
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/70—Type of control algorithm
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • the present subject matter relates generally to wind turbines and, more particularly, to a system and method for improving extreme load control for wind turbine components, such as rotor blades.
  • Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available and wind turbines have gained increased attention in this regard.
  • a modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades.
  • the rotor blades are the primary elements for converting wind energy into electrical energy.
  • the blades typically have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between its sides. Consequently, a lift force, which is directed from the pressure side towards the suction side, acts on the blade. The lift force generates torque on the main rotor shaft, which is connected to a generator for producing electricity.
  • the amount of power that may be produced by a wind turbine is typically limited by structural limitations (i.e. design loads) of the individual wind turbine components.
  • the blade root of a wind turbine may experience loads (e.g. a blade root resultant moment) associated with both average loading due to turbine operation and dynamically fluctuating loads due to environmental conditions.
  • loads e.g. a blade root resultant moment
  • Such loading may damage turbine components, thereby eventually causing the turbine components to fail.
  • the fluctuating loads can change day-to-day or season-to-season and may be based on wind speed, wind peaks, wind turbulence, wind shear, changes in wind direction, density in the air, yaw misalignment, upflow, or similar.
  • loads experienced by a wind turbine may vary with wind speed.
  • wind turbines utilize control systems configured to estimate loads acting on the wind turbine based on a wind turbine thrust.
  • the terms “thrust,” “thrust value,” “thrust parameter” or similar as used herein are meant to encompass a force acting on the wind turbine due to the wind.
  • the thrust force comes from a change in pressure as the wind passes the wind turbine and slows down.
  • Such control strategies estimate loads acting on the wind turbine by determining an estimated thrust using a plurality of turbine operating conditions, such as, for example, pitch angle, power output, generator speed, and air density.
  • the operating conditions are inputs for the algorithm, which includes a series of equations, one or more aerodynamic performance maps, and one or more look-up tables (LUTs).
  • the LUT may be representative of a wind turbine thrust.
  • a +/ ⁇ standard deviation of the estimated thrust may also be calculated, along with an operational maximum thrust and a thrust limit.
  • the wind turbine may be controlled based on a difference between the maximum thrust and the thrust limit.
  • the present disclosure is directed to a method for reducing loads, such as extreme loads, acting on at least one rotor blade of a wind turbine.
  • the method includes calculating, via a processor, a flapwise bending moment of the rotor blade(s). Further, the method includes calculating, via the processor, an edgewise bending moment of the rotor blade(s). The method also includes calculating, via the processor, an average load envelope of a blade root bending moment of the rotor blade(s) as a function of the flapwise bending moment and the edgewise bending moment of the rotor blade(s).
  • the method includes rotor blade(s) calculating, via the processor, an overall load envelope of the blade root bending moment of the rotor blade(s) as a function of the average load envelope and a future load estimation of the blade root bending moment of the rotor blade(s).
  • the method also includes implementing, via the processor, a control action when the overall load envelope is above a certain threshold.
  • calculating the flapwise bending moment may include calculating the flapwise bending moment as a function of an equivalent thrust acting on a rotor of the wind turbine and an overall length of the rotor blade(s). Further, in an embodiment, the method may include calculating the equivalent thrust acting on the rotor as a function of a thrust force, a rotor radius, and one or more processor variables, the one or more processor variables comprising at least one of a hub loading sensor measurement, d-q coordinate moments, or an aerodynamic location of where the thrust force is applied on the rotor blade(s).
  • calculating the edgewise bending moment may include calculating the edgewise bending moment as a function of two or more of the following parameters: a mass of the rotor blade(s), an acceleration due to gravity, a location of a center of gravity of the rotor blade(s), a hub connection distance, a low-speed-shaft mechanical torque, a rotor radius, a partial derivative of a rotor rotation with respect to time, and a rotor inertia.
  • calculating the average load envelope of the blade root bending moment as a function of the flapwise bending moment and the edgewise bending moment may include summing the squares of the flapwise bending moment and the edgewise bending moment and calculating the square root of the sum of the squares.
  • the method may include filtering the average load envelope of the blade root bending moment via at least one filter. More specifically, in an embodiment, filtering the average load envelope of the blade root bending moment via the at least one filter may include filtering the average load envelope of the blade root bending moment via two notch filters.
  • the two notch filters may be characterized by the transfer function that includes a gain attenuation, a damping factor, and a target frequency of the notch filters.
  • the method may include predicting the future load estimation of the blade root bending moment by calculating a future load envelope of the blade root bending moment as a function of one or more partial derivatives of thrust with respect to wind speed and rotor speed, an effective length of the rotor blade(s), and a travel time, the travel time equal to the shortest time required for an extreme blade root bending moment event on any rotor blade(s) of the wind turbine to travel downstream of a rotor plane to ensure the following rotor blade(s) is not impacted, the effective blade length corresponding to a location where an application of aerodynamic thrust produces a given blade root bending moment.
  • the method may also include calculating the travel time as a function of a distance being traveled by wind downstream of a rotor of the wind turbine after any of the rotor blades has experienced the extreme blade root bending moment event and an estimated wind speed.
  • calculating the overall load envelope of the blade root bending moment as a function of the average load envelope and the future load estimation may include summing the average load envelope and the future load estimation.
  • the method may also include calculating the aerodynamic thrust that produces the given blade root bending moment at the effective blade length and determining a distance between the aerodynamic thrust and a corresponding threshold.
  • the method may include determining the control action based upon the distance between the aerodynamic thrust and the corresponding threshold and a hysteresis band.
  • control action may include pitching one or more rotor blades of the wind turbine. More specifically, in an embodiment, pitching the one or more rotor blades may include at least one of collective pitching of a plurality of rotor blades of the wind turbine, independently pitching each of the plurality of rotor blades, cyclically pitching each of the plurality of rotor blades, fine pitching each of the plurality of rotor blades, or combinations thereof.
  • the present disclosure is directed to a system for reducing loads, such as extreme loads, acting on a rotor blade of a wind turbine.
  • the system includes a controller having at least one processor configured to perform a plurality of operations.
  • the plurality of operations may include but are not limited to calculating a flapwise bending moment of the rotor blade, calculating an edgewise bending moment of the rotor blade, calculating an average load envelope of a blade root bending moment of the rotor blade as a function of the flapwise bending moment and the edgewise bending moment of the rotor blade, filtering the average load envelope of the blade root bending moment via at least one filter, calculating an overall load envelope of the blade root bending moment of the rotor blade as a function of the average load envelope and a future load estimation of the blade root bending moment of the rotor blade, and implementing a control action when the overall load envelope is above a certain threshold.
  • the system may include any of the additional features as described herein.
  • FIG. 1 illustrates a perspective view of one embodiment of a wind turbine according to the present disclosure
  • FIG. 2 illustrates a simplified, internal view of one embodiment of a nacelle of a wind turbine according to the present disclosure
  • FIG. 3 illustrates a schematic diagram of one embodiment of a controller according to the present disclosure
  • FIG. 4 illustrates a perspective view of one embodiment of a wind turbine according to the present disclosure, particularly illustrating various axes of rotation and corresponding forces and moments acting on the wind turbine;
  • FIG. 5 illustrates a flow diagram of one embodiment of a method for reducing extreme loads acting on a rotor blade of a wind turbine according to the present disclosure
  • FIG. 6 illustrates a graph of one embodiment of the estimated MzB 1 , MzB 2 and MzB 3 and its respective envelope MzB env and the estimated MyB 1 , MyB 2 and MyB 3 and its respective envelope MyB env according to the present disclosure
  • FIG. 7 illustrates one embodiment of an equivalent plot of MrB 1 , MrB 2 and MrB 3 and the respective raw envelope M env raw according to the present disclosure
  • FIG. 8 illustrates a graph of one embodiment of the MrB envelope power spectral density according to the present disclosure
  • FIG. 9 illustrates a schematic diagram of one embodiment of the MrB envelope according to the present disclosure being filtered via two notch filters
  • FIG. 10 illustrates a graph of one embodiment of the estimated MrB envelope, particularly illustrating the raw MrB envelope compared to the filtered MrB envelope according to the present disclosure
  • FIG. 11 illustrates a schematic diagram of one embodiment of a rotor of the wind turbine according to the present disclosure, particularly illustrating the travel distance D tvl ;
  • FIG. 12 illustrates a schematic diagram of one embodiment of a rotor blade represented as a cantilever beam excited at the tip by the thrust force FzAero and particularly illustrating the effective blade length L bld eff ;
  • FIG. 13 illustrates a graph of one embodiment of the travel time (y-axis) versus time (x-axis) according to the present disclosure, particularly illustrating the constrained travel time
  • FIG. 14 illustrates a graph of one embodiment of the functional behavior of envelope-based MrB control according to the present disclosure.
  • the present disclosure is directed to improved systems and methods for improved extreme load control for wind turbine components, such as the rotor blades. More specifically, the method aims to use an envelope-based blade root bending moment control algorithm.
  • control strategy includes multiple sub-elements, including but not limited to the extraction of the blade root bending moment load envelope, a state machine, and a control action.
  • the blade root bending moment envelope extraction described herein provides a framework that detects the instantaneous envelope of the blade root moments for each rotor blade for determining the blade root bending moment load envelope that can be used in the envelope-based control of the wind turbine.
  • the envelope detection algorithm encompasses, at least, the extraction of the raw blade root bending moment envelope, a filtering process to remove unwanted frequency components from the raw blade root bending moment envelope, and the computation of a predicted or look-ahead envelope component to provide the algorithm with preview capabilities.
  • the wind turbine 10 generally includes a tower 12 extending from a support surface 14 , a nacelle 16 mounted on the tower 12 , and a rotor 18 coupled to the nacelle 16 .
  • the rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outwardly from the hub 20 .
  • the rotor 18 includes three rotor blades 22 .
  • the rotor 18 may include more or less than three rotor blades 22 .
  • Each rotor blade 22 may be spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy.
  • the hub 20 may be rotatably coupled to an electric generator 24 ( FIG. 2 ) positioned within the nacelle 16 to permit electrical energy to be produced.
  • the wind turbine 10 may also include a wind turbine controller 26 centralized within the nacelle 16 .
  • the controller 26 may be located within any other component of the wind turbine 10 or at a location outside the wind turbine.
  • the controller 26 may be communicatively coupled to any number of the components of the wind turbine 10 in order to control the operation of such components and/or to implement a correction action.
  • the controller 26 may include a computer or other suitable processing unit.
  • the controller 26 may include suitable computer-readable instructions that, when implemented, configure the controller 26 to perform various different functions, such as receiving, transmitting and/or executing wind turbine control signals.
  • the controller 26 may generally be configured to control the various operating modes (e.g., start-up or shut-down sequences), de-rate the wind turbine, and/or control various components of the wind turbine 10 as will be discussed in more detail below.
  • the generator 24 may be coupled to the rotor 18 for producing electrical power from the rotational energy generated by the rotor 18 .
  • the rotor 18 may include a rotor shaft 34 coupled to the hub 20 for rotation therewith.
  • the rotor shaft 34 may, in turn, be rotatably coupled to a generator shaft 36 of the generator 24 through a gearbox 38 .
  • the rotor shaft 34 may provide a low speed, high torque input to the gearbox 38 in response to rotation of the rotor blades 22 and the hub 20 .
  • the gearbox 38 may then be configured to convert the low speed, high torque input to a high speed, low torque output to drive the generator shaft 36 and, thus, the generator 24 .
  • Each rotor blade 22 may also include a pitch adjustment mechanism 32 configured to rotate each rotor blade 22 about its pitch axis 28 .
  • each pitch adjustment mechanism 32 may include a pitch drive motor 40 (e.g., any suitable electric, hydraulic, or pneumatic motor), a pitch drive gearbox 42 , and a pitch drive pinion 44 .
  • the pitch drive motor 40 may be coupled to the pitch drive gearbox 42 so that the pitch drive motor 40 imparts mechanical force to the pitch drive gearbox 42 .
  • the pitch drive gearbox 42 may be coupled to the pitch drive pinion 44 for rotation therewith.
  • the pitch drive pinion 44 may, in turn, be in rotational engagement with a pitch bearing 46 coupled between the hub 20 and a corresponding rotor blade 22 such that rotation of the pitch drive pinion 44 causes rotation of the pitch bearing 46 .
  • rotation of the pitch drive motor 40 drives the pitch drive gearbox 42 and the pitch drive pinion 44 , thereby rotating the pitch bearing 46 and the rotor blade 22 about the pitch axis 28 .
  • the wind turbine 10 may include one or more yaw drive mechanisms 66 communicatively coupled to the controller 26 , with each yaw drive mechanism(s) 66 being configured to change the angle of the nacelle 16 relative to the wind (e.g., by engaging a yaw bearing 68 of the wind turbine 10 ).
  • the wind turbine 10 may also include one or more sensors 48 , 50 for measuring various operating parameters that may be required to various blade moments as described in more detail below.
  • the sensors may include blade sensors 48 for measuring a pitch angle of one of the rotor blades 22 or for measuring a load acting on one of the rotor blades 22 ; generator sensors (not shown) for monitoring the generator 24 (e.g. torque, rotational speed, acceleration and/or the power output); sensors for measuring the imbalance loading in the rotor (e.g. main shaft bending sensors); and/or various wind sensors 50 for measuring various wind parameters, such as wind speed, wind peaks, wind turbulence, wind shear, changes in wind direction, air density, or similar.
  • the sensors may be located near the ground of the wind turbine, on the nacelle, or on a meteorological mast of the wind turbine. It should also be understood that any other number or type of sensors may be employed and at any location.
  • the sensors may be Micro Inertial Measurement Units (MIMUs), strain gauges, accelerometers, pressure sensors, angle of attack sensors, vibration sensors, proximity sensors, Light Detecting and Ranging (LIDAR) sensors, camera systems, fiber optic systems, anemometers, wind vanes, Sonic Detection and Ranging (SODAR) sensors, infra lasers, radiometers, pitot tubes, rawinsondes, other optical sensors, and/or any other suitable sensors.
  • MIMUs Micro Inertial Measurement Units
  • LIDAR Light Detecting and Ranging
  • SODAR Sonic Detection and Ranging
  • the term “monitor” and variations thereof indicates that the various sensors may be configured to provide a direct measurement of the parameters being monitored or an indirect measurement of such parameters.
  • the sensors may, for example, be used to generate signals relating to the parameter being monitored, which can then be utilized by the controller 26 to determine the actual parameter.
  • the controller 26 may include one or more processor(s) 58 and associated memory device(s) 60 configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). Additionally, the controller 26 may also include a communications module 62 to facilitate communications between the controller 26 and the various components of the wind turbine 10 . Further, the communications module 62 may include a sensor interface 64 (e.g., one or more analog-to-digital converters) to permit signals transmitted from the sensors 48 , 50 to be converted into signals that can be understood and processed by the processors 58 .
  • a sensor interface 64 e.g., one or more analog-to-digital converters
  • the sensors 48 , 50 may be communicatively coupled to the communications module 62 using any suitable means.
  • the sensors 48 , 50 are coupled to the sensor interface 64 via a wired connection.
  • the sensors 48 , 50 may be coupled to the sensor interface 64 via a wireless connection, such as by using any suitable wireless communications protocol known in the art.
  • the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits.
  • the memory device(s) 60 may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements.
  • RAM random access memory
  • CD-ROM compact disc-read only memory
  • MOD magneto-optical disk
  • DVD digital versatile disc
  • Such memory device(s) 60 may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 58 , configure the controller 26 to perform various functions including, but not limited to, determining one or more current wind turbine parameters of the wind turbine 10 based on the plurality of operating data, determining a maximum wind turbine parameter, transmitting suitable control signals to implement control actions to reduce loads acting on the wind turbine, and various other suitable computer-implemented functions.
  • the peak loads of the wind turbine 10 may vary between turbines, but in general, typically correspond to at least one of the following: the blade root resultant moment (e.g. M rB , which includes pitch and hub loads M xB , M yb , and M zb ), main shaft loads (e.g. M yr , M zr ), main bearing loads (e.g. M xr , M yr ), yaw drive loads (e.g. M xk ), yaw bolts/bearing/flange loads (e.g.
  • M rB which includes pitch and hub loads M xB , M yb , and M zb
  • main shaft loads e.g. M yr , M zr
  • main bearing loads e.g. M xr , M yr
  • yaw drive loads e.g. M xk
  • yaw bolts/bearing/flange loads e.g.
  • M yk , M zk or tower bending loads (e.g. M xt , M yt , and M zt ).
  • the peak loads as described herein may also include any additional loads experienced by the wind turbine 10 and that the loads illustrated in FIG. 4 are provided for example purposes only. Calculations of such forces and moments are further described herein.
  • FIG. 5 a flow diagram of method 100 for reducing extreme loads acting on a component of a wind turbine according to one embodiment of the present disclosure is illustrated.
  • the component may include, for example, one or more of the rotor blades 22 , the pitch bearing 46 , or the hub 20 of the wind turbine 10 .
  • the method 100 is described herein as implemented using, for example, the wind turbine 10 described above. However, it should be appreciated that the disclosed method 100 may be implemented using any other suitable wind turbine now known or later developed in the art.
  • FIG. 5 depicts steps performed in a particular order for purposes of illustration and discussion, the methods described herein are not limited to any particular order or arrangement.
  • One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods can be omitted, rearranged, combined and/or adapted in various ways.
  • the method 100 includes calculating, via the processor(s) 58 , a flapwise bending moment (e.g. MyB env ) of one or more of the rotor blades 22 .
  • the processor(s) 58 may calculate the flapwise bending moment of the rotor blade(s) 22 as a function of an equivalent thrust (e.g. F r ) acting on the rotor 18 and an overall length of the rotor blade(s) 22 (e.g. Rr-P HubCO ) e.g. using Equation (1) below:
  • MyB env F r *( P OPAeroLoc *Rr ⁇ P HubCO ) Equation (1)
  • the method 100 may include calculating the equivalent thrust F r acting on the rotor 18 as a function of a thrust force, a rotor radius, and one or more processor variables.
  • the processor variable(s) may include a hub loading sensor measurement, d-q coordinate moments, or an aerodynamic location of where the thrust force is applied on the rotor blade(s) 22 .
  • the processor(s) 58 is configured to calculate the equivalent thrust F r using Equation (2) below:
  • the method 100 further includes calculating, via the processor(s) 58 , an edgewise bending moment (MzB env ) of the rotor blade(s) 22 .
  • the processor(s) 58 is configured to calculate the edgewise bending moment of the rotor blade(s) 22 as a function of two or more of the following parameters: a mass of the rotor blade(s) 22 , an acceleration due to gravity, a location of a center of gravity of the rotor blade(s) 22 , a hub connection distance, a low-speed-shaft mechanical torque, a rotor radius, a partial derivative of a rotor rotation with respect to time, and a rotor inertia.
  • the processor(s) 58 is configured to calculate the edgewise bending moment of the rotor blade(s) 22 using Equation (3) below:
  • MzB env P BladeMass * - S ⁇ G * ( P CMloc - P HubCO ) + LSSMechTrq 3 * ( Rr - P HubCO ) Rr + dWr * P Jr 3 Equation ⁇ ⁇ ( 3 )
  • the method 100 further includes calculating, via the processor(s) 58 , an average load envelope of a blade root bending moment of the rotor blade(s) 22 as a function of the flapwise bending moment and the edgewise bending moment of the rotor blade(s) 22 .
  • the processor(s) 58 is configured to calculate the average load envelope by summing the squares of the flapwise bending moment and the edgewise bending moment and calculating the square root of the sum of the squares, as shown in Equation (4) below.
  • MrB env raw ⁇ square root over (MyB env 2 +MzB env 2 ) ⁇ Equation (4)
  • FIG. 6 illustrates an example graph 200 of the estimated MzB 1 , MzB 2 and MzB 3 202 , 204 , 206 for three rotor blades and its envelope MyB env 208 . Further, as shown, the graph illustrates estimated MyB 1 , MyB 2 and MyB 3 210 , 212 , 214 and its respective envelope MxB env 216 .
  • FIG. 7 illustrates an equivalent plot 300 of MrB 1 , MrB 2 and MrB 3 302 , 304 , 306 and the respective raw envelope MrB env raw 308 .
  • the raw MrB estimated envelope 402 is dominated by the 3P component, with lesser peaks at 6P and 9P. These higher harmonics may become less (respectively, more) noticeable in presence (respectively, absence) of wind misalignment.
  • the single blade MrB estimate 404 is generally dominated by the 1P and blade flap frequency components.
  • Such a frequency shifting generally occurs because the envelope carries the average frequency content of the three rotor blades.
  • the 1P frequency is shifted by the number of blades, i.e. to 3P. This is called the “aggregation phenomenon” and may be typical of the envelope extraction.
  • the envelope-based MrB control of the present disclosure should be less sensitive to changes of (at least) the 3P and (additionally) the 6P harmonics so as to reduce the controller response to rotor rotation driven MrB excitation.
  • mitigation of the 3P and 6P harmonics is accomplished through filtering the average load envelope of the blade root bending moment via at least one filter.
  • the processor(s) 58 may filter the average load envelope of the blade root bending moment via one or more notch filters, such as two notch filters 500 , 502 .
  • the notch filter(s) 500 , 502 may be characterized by the transfer function of Equation (5) below:
  • the attenuation level g can be set equal to 0.25 (i.e. only 25% of original frequency content at ⁇ n will be kept) and d can be set to be 0.707 for both the 3P and 6P notch filters. Both parameters can be selected to provide the best possible attenuation and the least delay. Further, such parameters may or may not be turbine specific.
  • An example of a graph 500 of one embodiment of the filtered envelope is shown in FIG. 10 , with the raw MrB envelope being labeled 502 and the envelope after application of both notch filters at 3 P and 6 P being labeled 504 .
  • MrB 1 , MrB 2 , and MrB 3 of the respective rotor blades are labeled as 506 , 508 , and 510 , respectively.
  • the method 100 also includes predicting, via the processor(s) 58 , a future load estimation of the blade root bending moment of the rotor blade(s) 22 .
  • the processor(s) 58 may calculate a future load envelope of the blade root bending moment as a function of one or more partial derivatives of thrust with respect to wind speed and rotor speed, an effective length of the rotor blade, and a travel time, the travel time equal to the shortest time required for an extreme blade root bending moment event on any rotor blade of the wind turbine to travel downstream of a rotor plane to ensure the following rotor blade is not impacted, the effective blade length corresponding to a location where an application of aerodynamic thrust produces a given blade root bending moment.
  • the processor(s) 58 can calculate a travel distance T tvl using Equation (6) below:
  • the travel distance D tvl generally refers to the distance between two adjacent blades 22 at the effective blade length, L bld eff and can be calculated using Equation (7) below:
  • the effective blade length is the location where the application of the aerodynamic thrust produces the given MrB blade root moment.
  • FIG. 12 illustrates a schematic diagram of one embodiment of this concept.
  • the travel time T tvl as described herein generally refers to the shortest time required for an extreme MrB event on any rotor blade(s) 22 to travel downstream of the rotor plane to ensure the following blade(s) 22 is not impacted.
  • Such travel time may also be equal to the minimum time before the pitch commanded by the control algorithm described herein begins to decay to fine pitch. This travel time ensures that the extreme MrB event is far enough downstream to avoid impacting the following blade, being located a distance D tvl away from the blade where it has caused the extreme event.
  • T tvl reaches its maximum at cut-in wind speed.
  • the envelope-based MrB control algorithm is most likely to be active around nominal wind speed. Therefore, in an embodiment, as shown in the graph 600 of FIG. 13 , the upper bound of this travel time can be set to the rated wind speed 602 of the wind turbine 10 .
  • the MrB envelope prediction term Given the travel time, T tvl , the effective blade length, L bld eff , and the partial derivatives of the estimated thrust in terms of both the wind speed and the rotational speed, the MrB envelope prediction term can be calculated using Equation (9) below:
  • MrB env pred [ T tvl ⁇ max ⁇ ( 0 , ⁇ FzAero ⁇ v ⁇ v . + ⁇ FzAero ⁇ ⁇ ⁇ ⁇ . ) ] ⁇ L bld eff Equation ⁇ ⁇ ( 9 )
  • the MrB env pred prediction term is configured to adjust the MrB envelope by an amount equal to the predicted thrust T tvl in the future, allowing the processor(s) 58 to reach to and mitigate loads a short time in the future.
  • the method 100 further includes calculating, via the processor(s) 58 , an overall load envelope (e.g. MrB env ) of the blade root bending moment of the rotor blade(s) 22 as a function of the average load envelope and the future load estimation.
  • an overall load envelope e.g. MrB env
  • the processor(s) 58 may be configured to calculate the overall load envelope of the blade root bending moment by summing the average load envelope and the future load estimation.
  • the full MrB envelope, including the prediction term may be calculated by the processor(s) 58 using Equation (10) below:
  • MrB env MrB env filt +MrB env pred Equation (10)
  • the method 100 includes implementing, via the processor(s) 58 , a control action when the overall load envelope (MrB env ) is above a certain threshold.
  • the control action may include pitching the rotor blade(s) 22 .
  • pitching the rotor blade(s) 22 may include collective pitching of a plurality of rotor blades 22 of the wind turbine 10 , independently pitching each of the plurality of rotor blades 22 , cyclically pitching each of the plurality of rotor blades 22 , fine pitching each of the plurality of rotor blades 22 , or combinations thereof.
  • the method 100 may also include calculating the aerodynamic thrust that produces the given blade root bending moment at the effective blade length and determining a distance between the aerodynamic thrust and a corresponding threshold.
  • the method may include determining the control action based upon the distance between the aerodynamic thrust and the corresponding threshold and a hysteresis band.
  • the processor(s) 58 can use Equations (11)-(14) to calculate the following equivalent thrust forces parameters:
  • equivalent thrust forces are used by the processor(s) 58 to calculate the pitch required to mitigate MrB load exceedances. More specifically, in an embodiment, the thrust force(s) described herein create the blade root moment when imposed at L bld eff and therefore must be calculated. Similarly, the thresholds are also expressed in terms of equivalent thrust forces to evaluate exceedance and hysteresis conditions.
  • HystMrB env P MrBHysteresis ⁇ FzAero eq MrB threshold Equation (14)
  • the control algorithm of the processor(s) can take a different action based upon the size of these distances between actual moments and thresholds.
  • a state-machine realization can be used to determine the appropriate control action, with states defined based upon the instantaneous value of the MrB envelope relative to the threshold and hysteresis band.
  • FIG. 14 a graph of envelope-based MrB control is illustrated according to the present disclosure. More specifically, FIG. 14 illustrates how the envelope-based MrB control operates and displays the behavior of MrBPitch and FinePitch relative to the value of the MrB envelope compared to the threshold.
  • MrBPitch is defined as an additional collective pitch signal equivalent to the load exceedance, calculated using the derivative of the thrust with respect to pitch.
  • the functionality may be temporarily disabled to prevent it from reducing the effectiveness of the envelope-based MrB control strategy in mitigating the extreme blade root loads.
  • the algorithm can switch to state 2 and a timer can begin to increment (this timer is reset in all other states).
  • the processor(s) 58 can remain in this state if the envelope is within the hysteresis band and the timer remains in the below travel time, T tvl .
  • An additional condition then allows entering state 2 only if prior to this state the algorithm was in state 3 or exactly in state 2 . Further, as shown in the illustrated embodiment, while in state 2 , MrBPitch is held constant.
  • the algorithm can exit state 2 and enters state 1 .
  • the MrBPitch begins to decay towards fine pitch, and the algorithm remains in state 1 until MrBPitch is within a certain degree, such as 0.05 degrees, of the fine pitch.
  • the MrB envelope control algorithm also allows for defining a saturation level on MrBPitch via one or more parameters defined by the processor(s) 58 . This represents the largest pitch angle the algorithm can request to prevent extreme MrB from exceeding the design limit in the extreme load case.
  • a method for reducing loads acting on at least one rotor blade of a wind turbine comprising:
  • calculating the flapwise bending moment further comprises calculating the flapwise bending moment as a function of an equivalent thrust acting on a rotor of the wind turbine and an overall length of the at least one rotor blade.
  • Clause 3 The method of claim 2 , further comprising calculating the equivalent thrust acting on the rotor as a function of a thrust force, a rotor radius, and one or more processor variables, the one or more processor variables comprising at least one of a hub loading sensor measurement, d-q coordinate moments, or an aerodynamic location of where the thrust force is applied on the at least one rotor blade.
  • calculating the edgewise bending moment further comprises calculating the edgewise bending moment as a function of two or more of the following parameters: a mass of the at least one rotor blade, an acceleration due to gravity, a location of a center of gravity of the at least one rotor blade, a hub connection distance, a low-speed-shaft mechanical torque, a rotor radius, a partial derivative of a rotor rotation with respect to time, and a rotor inertia.
  • filtering the average load envelope of the blade root bending moment via the at least one filter further comprises filtering the average load envelope of the blade root bending moment via two notch filters.
  • Clause 8 The method of claim 7 , wherein the two notch filters are characterized by a transfer function comprising a gain attenuation, a damping factor, and a target frequency of the notch filters.
  • Clause 10 The method of claim 9 , further comprising calculating the travel time as a function of a distance being traveled by wind downstream of a rotor of the wind turbine after any of the at least one rotor blades has experienced the extreme blade root bending moment event and an estimated wind speed.
  • Clause 13 The method of claim 12 , further comprising determining the control action based upon the distance between the aerodynamic thrust and the corresponding threshold and a hysteresis band.
  • control action comprises pitching one or more rotor blades of the wind turbine.
  • pitching the one or more rotor blades further comprises at least one of collective pitching of a plurality of rotor blades of the wind turbine, independently pitching each of the plurality of rotor blades, cyclically pitching each of the plurality of rotor blades, fine pitching each of the plurality of rotor blades, or combinations thereof.
  • a system for reducing loads acting on at least one rotor blade of a wind turbine comprising:
  • a controller comprising at least one processor configured to perform a plurality of operations, the plurality of operations comprising:
  • calculating the flapwise bending moment further comprises calculating the flapwise bending moment as a function of an equivalent thrust acting on a rotor of the wind turbine and an overall length of the at least one rotor blade.
  • calculating the edgewise bending moment further comprises calculating the edgewise bending moment as a function of two or more of the following parameters: a mass of the at least one rotor blade, an acceleration due to gravity, a location of a center of gravity of the at least one rotor blade, a hub connection distance, a low-speed-shaft mechanical torque, a rotor radius, a partial derivative of a rotor rotation with respect to time, and a rotor inertia.
  • filtering the average load envelope of the blade root bending moment via the at least one filter further comprises filtering the average load envelope of the blade root bending moment via two notch filters.
  • control action comprises pitching one or more rotor blades of the wind turbine, wherein pitching the one or more rotor blades further comprises at least one of collective pitching of a plurality of rotor blades of the wind turbine, independently pitching each of the plurality of rotor blades, cyclically pitching each of the plurality of rotor blades, fine pitching each of the plurality of rotor blades, or combinations thereof.

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CN202110385951.5A CN113530757A (zh) 2020-04-09 2021-04-09 针对风力涡轮转子叶片的改进极端负载控制的系统及方法

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US20110158806A1 (en) * 2009-04-15 2011-06-30 Arms Steven W Wind Turbines and Other Rotating Structures with Instrumented Load-Sensor Bolts or Instrumented Load-Sensor Blades
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